Stabilizers for photographic emulsions



STABILIZ ERS FOR PHOTOGRAPHIC EMULSIONS Filed Dec. 15, 1945 L\6H'TSENsn'wE EmuLsmN LAYER COLLOWNM. LAYER I CONTAINING A HYDROXY-l,3, sl'rrmllIllHHIIIIIIIIHHIIIHIIIlllllllllllHllIHllllllllllllllllllu f M A--Tm-AzMNDouzmz SUPPORT Fae. 2.

CoLLowAL LAYER CONTAINING A HYDROXY-l, 3, 4--TR\AZA\NDOL\ZINE Z wEMULSAQN LAYER SUPPORT FAG. 3.

LJGHT SENSFHVE EMULS\ON LAYER JNVENTORS NEWTON Hamgmm WALTER KELLY JR.

% TORfiEYS Patented July 6, li348 s'rAmnlznns ronirno'ro EMULSIONS:

GRAPHIG Newton Heimbach and Walter ,Kelly,s.lr., Bin'g hamton, N. Y.,assignors to GeneraliAniline 8;

Film Corporation, New York, N; Y., a-corporation of Delaware ApplicationDecember 15, 1945, SeriaLNo. 635,334

1 1- Glaims. (o1. 95-1) This invention relates to the stabilization oflight-sensitive silver-halide emulsions, and more particularly to theuse of reaction products obtained by a condensation of a B-keto ester, amalonic ester or a mononitrile ofamalonic ester, with a3--amino-1,2,4-triazole as stabilizers for silver-halide emulsions.

It is known in the art that llght -sensitive emulsions, such as gelatinsilver-halide emulsions have a decided tendency to: fog. The fog may beof two types, namely, yellow fog and chemical (gray) fog. Theyellow'fog, sometimes referred to as color -fg or dichroic fog, isessentially a colloidal deposit of silver, thecolor intensity andgeneral appearance of which are determined by the minute particle sizeand degree of subdivision. The fog is chiefly yellowxin colorandais mostapparent in the lighter portions of a negative. The color may vary,however, and the colloidal silver particles may, for example, appeargreen by refiected light and yellow or; red by transmitted light. Theso-called chemical fog, or gray fog, on the other hand, is the morecommon and is formed in a number of ways. It may "be caused by prematureexposure, by excessive ripening of the emulsions, or. by the.storageofthe fllm, particularly at high temperatures or for unusuallylong periods of time.

The primary object of the present invention is to provide stabilizers orfog inhibiting agents which tend to prevent the formation of chemicalfog in light-sensitive silver-halide emulsions.

A further object is to providest'abilizers or anti-fogging agentsforlight-sensitive silver-halide emulsions, which do not lower thesensitivity of the emulsion,'and which increase its stability.

Still further objects and advantages will appear from the followingspecification.

We have found that the-above objects are accomplished by the use ofreaction products obtained by a condensation of a B-keto ester, amalonic ester, or a mononitrileof a m-alonic ester with anaminotriazole. The references in Bellstein have advanced the namehydroxy-l,3,4- triazaindolizines for these reaction products whichimplies aistructureiof-athe following general formula:

" wherein R is hydrogen, alkyLe'. g., 'methyLethyl,"

" or heterocyclic radical propyl, isopropyl', butyl, arnyl, andtheilike, a1icyclic,'e. g., cyclopentyl, cyclohexyl; and the like, aryl,e. g., phenyl, naphthyl; diph'enyl, etch;

or a heterocyclic radical, e. g., pyridyl, furyl 'pyrryl, pyrazolyl, andthe like, R1 is hydrogen" or an alkyl, alicyclic, aryl, or heterocyclicradical of the same value as and; R2 is either amino,hydroxy,.canba1koxy, e. g., carbethoxy, carbpropoxy, and'the like, or analkyl, alicyclic of the same value as R. However, when R and R1 arehydrogen, R2 must be one of the radicals other than alkyl.

The method. for the preparation ofthe hydroxy-1,3,4-triazaindolizines isgiven in the lit erature. The method consists of heating 1 mol,

of a ,B-keto ester, a malonic ester, or a mononitrile of a malonicester, with 1 mol of a 3- amino-1,2,4-triazole offthe following generalformula:

' wherein Ris hydrogen, alkyl, e. g., methyl, ethyl,

propyl, and the like, or anwaryl radical, e. g..-,

phenyl, naphthyl, diphenyl, and the like.

Suitable p-keto esters are, for example, acetoacetic ester,benzoylacetie esterya-ethyl-acetoacetic ester, a-phenyl'acetoaceticester, ethyl nicotinoacetic ester, y-cyclohexanoacetic ester, and thelike.

As examples of suitable malonic esters and mononitriles thereof,according to this invention may be mentioned, dimethy-l malonate;diethyl malonate, diethyl methylmalonate, diethyl ethylmalonate, methylcyan'oacetate, ethyl cyano acetate, ethyl a-methyl cyanoacetate, and thelike.

As suitable 3eami'no-L2 i4-triazoles may be mentioned,3"-amino-5-methyl-l,2,4=triazole, 3- amino-5-phenyl-1,2,4etriazole,,andthe like.

The condensation between the'p-keto ester, a malonic ester, or amononitrile of a malonic ester, and the.3ramino-l,2,4etriazole, is,carriedout by heating the reaction components at a'temperature rangingfrom C. to C., preferably at, reflux temperature in the presence of asuitable solvent, such as glacial acetic acid, pyridine, or alcoholicalkali, fora period of three to eight hours. During this treatment,water and alcohol are formed. As the condensation or ring closurebetween thereactants, proceeds, the final product either precipitatesfrom'solution during the courseot the reactionorisremoved by dilutwereapplied in the preparation of compounds 3' to 7 and 11 to 18, inclusive.The method for the preparation of the products of the type illustratedby compound 9 consists of heating one mol of a malonic ester with 1 molof a 3-amin0-1,2,4- triazole, under the same reaction conditions asgiven in the above references.

The method for.

the preparation of the products of the type '11- lustrated by compound10 consists of heating 1 mol 0d. a mononitrile of a malonic ester with 1mol of a 3-amino-1,2,4-triazo1e.

The 3-amino-1,2,4-triazoles, p-keto esters ma Ionic esters andmononitriles thereof, arerwell known to the art, and the methods fortheir preporation need not be described herein.

Specific compounds which have been prepared according to the aboveprocedure with their probable formulae are the following:

GHr- C==N 7-hydroxy-6-ethyl-5-methyl-1,3,4-triazaindolizine7-hydroxy-6-ethyl-2,6-dlmethyl-1,3,4-trlazaindolizine OL LN7-hydroXy-2-methyl-E-phenyl-l,3,4-triazaindoliz1ne 7-11 amx -s nen l-i,al-mmmdbnzme- 4 on o 7-hydwoxy-2,5-diphenyl-l,3A-triazaindolizine7-hydroxy-2-isopropyl-5-methyl-1,SA-triazaindolizine Y i i O-CH: on '=N7-hydroxy- ,G-dimethyl-l,3,4-triazaindolizine %C\, 7 HC N--I l'\5,7dihydroxy-1,d-triazaindolizine HaN- i\ C==N N 7-hydroxy-5-arnino-1,3,4-triazaindolizine HeCaO O C-l N7-hydroxy-B-carbethoxy-l,3,4-triazaindo1izine 110 \N CHr-OH:

7-hydroxy-Z-cyclohexyl-B-methyl-1,3,4-triazaindolizine7-hyaay-2n-mry11=maria-i,gl sszanaatae 7-hydroxyfi-cyclohexyl-l,3,4-triazaiudolizine carom.

\ HO-O 7-hydroxy-S-niethyl-B-phenyl-l,3,4-triazaindolizine In thepreparation of an emulsion containing the stabilizers used according toour invention, a solution of the stabilizer in a suitable solvent, suchas alcohol or an alcohol-water mixture, adjustedto a neutral" orslightly alkaline, pH, i. e., p I-I 7.'5 to 10, is made up, and the.solution..mixed with'tlie emulsion at any pointduring it'sprepae ration,but preferably during ripening or just prior to coating inconcentrations varying from mg. to 500 mg. per liter of emulsion. Theactual concentration employed will depend upon the type of emulsion usedand may vary somewhat with the particular compound employed.

The method of testing the stabilizers employed in the following examplesconsists of coating two .film strips', ,such as cellulose acetate, withthesa'me emulsion, one-withlandone-withoutany stabilizer, storing theemulsionsgin an incubator" for six days at 50 C., then exposing,developing; liking, and washing the same under standard conditions. Thefog density or blackening produced in the unexposed areas in the twoemulsions is then measured in a transmission densitometer of standardtype.

The followingexamples. will serve to illustrate certain ways in whichthestabilizers of our ingave a. fog of 0.28' density. Another filmicoatedwith the sameemulsion containing an addition of mgl'of Compound 12 per1000'-cc. of emulsion equivalenttoabout. 50 grams of silverehalid'e, anddeveloped under the same conditions, afterthe same incubation, gave afog of only 0.08 density.

Example II Example I was repeated with the exception that an equivalentquantity of Compound 5 was: substituted for-Compound 12. The results'obtailied' were almost identical with those obtained in Example-I. l,

Example III Example I was again repeated with theexception tliat"l5mgfiof Compound 1 were'substituted for 1-00 ing. -of Compound 12.After-incubation and development, the emulsion containing Comipoun'd 1gave afog' of only 0.1. I

Further experiments' have shownthat emu];- sio'ris containingstabilizers in accordance with our invention have not only improvedkeeping qualities (i. e., a reduction in thei'og produc d by incubationor by long storage) but have greatly diminished and, in some casescompletely eliminatedchanges of speedto which some emulsions aresusceptible. v

The stabilizers, which we have described and employed, may be used invarious kinds of emul sio'ns'. In addition to being useful inorthoehromaticandpan'chromatic emulsions, they may also be used innon-sensitized emulsions and X-ray emulsions. If used with sensitizingdyes they may be added to the emulsion before or after the dyes areadded. The dispersing agents for the silver-halides may be gelatin orother colloid such aswater-soluble cellulose derivatives e. g., hydroxyethyl cellulose, methyl cellulose, carboxy-oxy-cellulose, low acetylvalue cellulose acetate, and the like. Th stabilizers may alsobeemployed. in gelatin or other colloid, such as polyar'nides or amixture of gelatin with a poly-v arnide as described in United. States-Patent 2;289,'7.'Z5; 'po1yvinyl alcohol andjelling compound as describedin United States Patent 2,249,537, pol'winyl acetaldehyde acetal resinsand. partially hydrolyzed acetate resins described in United StatesPatents 1,939,422 and 2,036,092; cellulosefderivatives, e.g.,;cellulosenitrate, cellulose acetatethe lower. fatty acid esters ofcellu lose .includingsimple and mixed esters, ,ethers of cellulose, andthe like, as an under or overcoat for the emulsion, or as backing layerfor the support. Moreover, they may be incorporated in the support forthe sensitive emulsion layer or in an intermediatelayer between thesensitive emulsion layer and the support, such as the baryta coatingcommonly used in photographic papers, or they may be, incorporated in aprotective layer coated upon the emulsion surface, or the otherwisefinished photographic material may be bathed in an alcohol oralcohol-water solution containing the stabilizer.

In the .accompanying drawing the "various figures; are enlarged section,views of photo graphic. ,materials: having. anti-fogging layers madeaccording to our inventionn incorporated directly into the 7 As shown inFigure 1, the support 1-, which may be of any suitable material such aglass, cellulose ester, synthetic resin, or paper, is provided with ananti-fogging layer 3 ,cntaining one of thehydroxy-1,3,4-triazaindolizines referred to above. The light sensitiveemulsion layer 2 is attached to the anti-fogging layer 3.

Figure 2 illustrates a similar material in which the support I is coatedwith a light-sensitive emulsion layer 2, and on the latter side there isprovided an anti-fogging layer 3 containing one of saidhydroxy-1,3,4-triazaindolizines.M

Figure 3 illustrates a film or plate of which the support I bears on oneside the light-sensitive emulsion layer 2, and on the other side anantifogging layer 3 containing one of said hydroxy-1,3,4-triazaindolizines. I a

"Figure 4 illustrates a film, plate, or paper of which the support I isprovided with the lightsensltive emulsion layer 2 containing asanantifogging layer one of said hydroxy-1,3,4-triazaindolizines. 1 Sincethe presence of these new; compounds tends to prevent chemical fogwhether they are emulsion, added to a separate surface or substratumlayer, it is understood that the term photographic material as employedherein and in the appended claims, is used in ageneric sense to includeeach of these possible applications. Various modifications of thisinvention will occur to persons skilled in the art and it is, therefore,understood that the patent granted shall only be limited by the appendedclaims. 1 We claim: 1. A photographic material comprising a base and alight-sensitive silver-halide emulsion carried thereby, saidphotographic material containing, in fog inhibiting amount, a compoundof the general formula:

3. A photographic material comprising a base and a light-sensitivesilver-halide emulsion carried thereby, said photographic materialcontaining,:1n fog inhibiting amount, a compound of the followingformula: 1

5. A photographic material comprising a base and a light-sensitivesilver-halide emulsion containing, in fog inhibiting-amount, a compoundof the general formula:

wherein R and R1 are members selected from the class consisting ofhydrogen, alkyl, aryl, alicyclic,

and heterocyclic groups, and R2 is a member selected from the classconsisting of amino, hy-

droxy, alkyl, alicyclic, aryl, and heterocyclic groups, R2 being a groupother than alkyl when R and R1 are hydrogen.

6. A photographic material comprising a lightsensitive silver-halideemulsion containing, in fog inhibiting amount, a compound of thefollowing formula:

7. A photographic material comprising a lightsensitive silver-halideemulsion containing, in fog inhibiting'amount, a compound of thefollowing formula: V

8. A photographic material comprising alightsensitive silver-halideemulsion containing,-in

10 11. A photographic gelatino silver-halide emulsion containing fromabout 25 mg. to about 500 mg. per liter of emulsion of a compound of thefollowing formula:

9. A photographic gelatino silver-halide emulsion containing from about25 mg. to about 500 mg. per liter of emulsion of a compound of thefollowing formula:

HO/ \N-N HO/ \N-N l l on (L l on C=N/ m =N/ N NEWTON HEIMBACH.

10. A photographic gelatino silver-halide emulm WALTER KELLY sioncontaining from about 25 mg. to about 500 mg. per liter of emulsion of acompound of the following formula:

REFERENCES CITED The following references are of record in the file ofthis patent:

20 UNITED STATES PATENTS o1mc \N-N Number Name Date 2,390,707 HeimbachDec. 11, 1945 0113-0 C=N/

